M&S says

Sleek and modern, our skinny fit trousers form an elegant foundation for any smart outfit. Whether worn in the workplace or to special occasions, these men’s suit trousers are a dapper neutral with a streamlined cut and silhouette. They’re machine washable for convenience, with a classic flat front design. Finished off with pockets and a hook, bar and zip fastening, they also feature built-in Buttonsafe™ technology to keep them looking new for longer.